#include <iostream>
#include <fstream>
#include <cmath>

using namespace std;

ifstream fi("fractii.in");
ofstream fo("fractii.out");

long long int phi[1000001];

void indicator(long long int n)
{
	for (int i = 1;i <= n;++i)
		phi[i] = i - 1;
	for (int i = 2;i <= n;++i)
	{
		for (int j = 2 * i;j <= n;j += i)
			phi[j] -= phi[i];
	}
}

int main()
{
	int n;
	fi >> n;
	long long int sol = 0;
	indicator(n);
	for (int i = 1; i<= n;i++)
		sol += phi[i];
	fo << 2 * sol + 1;


	return 0;
}